PROJECT 2 - ENVIRONMENTAL PROJECT 2 ? EP2 - PROJECT SUMMARY Abandoned uranium mines (AUM) situated on the tribal lands of the Navajo Nation and Laguna pueblo represent a major source of environmental contamination that threatens public health as a result of mobilization of toxic metals mixtures bearing uranium (U), vanadium (V), copper (Cu), arsenic (As). The transport of toxic metals mixtures into the air, and the potential for inhalational exposures, has never been investigated in a rigorous manner. The proposed research will investigate the potential exposure hazards to toxic metals mixtures resulting from inhalation of particulate matter (PM) derived from three different AUM sites located on Navajo Nation on Laguna Pueblo tribal lands in New Mexico and Arizona. The project will address the two specific aims: 1) Defining the physical, chemical and mineralogic profile of metals mixtures in AUM- impacted soils and assessing vulnerability to transport by wind; and 2) Developing a process model for the resuspension and transport of metal-bearing PM from AUM sites to estimate exposure risks for nearby vulnerable communities. For the process model, we will a) ascertain the particle size distributions and mineralogic characteristics of metal-bearing PM originating from AUM sites and the exposure potential to vulnerable populations living in the regional airshed under varied meteorological conditions; and b) conduct source-receptor modeling for the region, integrating information from three performance sites and deriving long-term estimates for Navajo community members. The proposed research will utilize state-of-the-art monitoring, chemical, imaging and atmospheric modeling techniques to provide a comprehensive dataset on the concentrations, speciation, valence, solubility, etc., of metals in different size fractions down to the nanoparticle scale that are essential to evaluate the potential toxicity and inhalation exposure risk for PM. The results will reduce uncertainty regarding the metal content, exposure concentrations, and sources of AUM- related PM exposures in risk reduction strategies.